Insulation displacement connector

ABSTRACT

An IDT connector ( 1 ) is provided which includes: a base housing ( 3 ) having a terminal ( 19 ) to which a wire ( 21 ) is press-fit; a cover housing ( 5 ) mounted to the base housing ( 3 ) and having a wire insertion hole ( 29 ) into which the wire ( 21 ) is inserted; a wire holder ( 31 ) which is provided to the cover housing, for pressing the wire that is to be press-fitted to the terminal; and an IDT contact slot extending orthogonal to the wire insertion hole and formed adjacent to the wire holder with respect to the longitudinal direction of the wire insertion hole.

BACKGROUND OF THE INVENTION

The present invention relates generally to a connector used forconnecting insulated electric wires to various electrical parts or aprinted circuit board, or for interconnecting a plurality set ofelectrical wires.

A connector with Insulation Displacement Technology Connection (“IDT”)has been widely used for making a permanent electrical interface betweena wire and a contact of a connector. In this method, insulated wires areforced into a slot smaller in width than the diameter of the innerconductor of the wire. The sharp thin edges of the slot displace theouter insulation and electrical continuity is secured. The slot of theIDT terminals typically have V or U-shaped slots obtained by punchingsheet metal, and the wires and the IDT terminals are connected with eachother by press-fitting them together. When press-fitting the wires asdescribed above, the wires are press-fit into the V or U-shaped slot sothat the IDT terminals pierce the outer insulations of the wires tobring the inner conductors thereof and the terminals into contact witheach other, thereby establishing electrical contact between theterminals and the wires.

In some other types of connectors, it is necessary to perform aninsulation removal process using a special tool such as a stripper atthe time of connection to the terminals. By using the above-describedIDT connectors, there is an advantage in that the insulation removal maybe dispensed with.

Incidentally, by merely press-fitting the wire into the slot of the IDTterminal, there is a fear that the wire in the IDT terminal drops off,due to vibrations generated during the use of an apparatus to which theIDT connector is applied, or due to an external force such as a tensiongenerated on the wire.

In order to solve this problem, there are prior arts such as JapaneseUtility Model laid-Open Publication No.Sho59-080971. In this prior art,the connector comprises wire pressing means for pressing on the wire,which has been pushed into the slot of the IDT terminal, within the slotin the pushing direction of the wire. According to such a connector, awire that is about to be press-fitted into the slot of the IDT terminalis further forcibly pressed on by the wire pressing means, therebypreventing the wire from dropping off.

However, with the above connector, the wire is pressed on by the wirepressing means irrespective of the manner in which the wire is insertedin the IDT terminal, for example, even when its position is deviatedfrom the center of the IDT slot. As a result, excessive strain may beexerted on the entire or part of the wire conductor, resulting in astress concentration. Consequently, there is a fear that one of thefollowing problems occur: a decrease in the sectional area of theconductor occurs which causes an increase in the resistance of theterminal-wire connection; the biased state causes a gap to be producedso that a part of the conductor does not come into contact with the IDTterminal; and due to the breaking of the wire, oxidation occurs due tomoisture present in the air, thus reducing durability and causing avariation in the resistance value.

The present invention is therefore directed to a solution of theabove-described problems.

SUMMARY OF THE INVENTION

It is a general object of the present invention to achieve IDT contactof the wire while retaining it properly in its normal and right positionand also prevent excessive strain from being exerted on the conductor ofthe wire, thereby preventing a change in the contact resistance value ora degradation of the conductor.

In order to attain the above object, a connector of the presentinvention is constructed as described below. That is, the inventionprovides an IDT connector including: a base housing having fixed thereinIDT terminals to which wires applied with outer insulation ispress-fitted; a cover housing which is mounted to the base housing andhas a guide hole into which the wire is inserted; and a wire holderwhich is provided to the cover housing and retains the wire that is tobe inserted into the guide hole, in which the cover housing has a wirenormal-position fixing means for fixing the wire in a normal positionwithin the guide hole with respect to a connection direction of the wire(insertion direction of the wire), and wire connection is performed bydisplacing the wire, which is fixed in the normal position within theguide hole by the wire normal-position fixing means, into an IDT contactedge of the IDT terminal while retaining the wire in the wire holder.

According to the above arrangement, the insertion of the wire into theguide hole provided in the cover housing serves to ensure fixing of thewire in its normal position with respect to the wire connectiondirection. Further, while this state is being maintained by the wireholder, the cover housing provided with the wire holder moves into thebase housing so that the wire is fixed to an appropriate position of theIDT terminal, thereby performing wire connection by the IDT contact inan extremely accurate manner. That is, because the wire can be broughtinto contact with the IDT terminal while remaining fixed in its normalposition and in a state in which it is being pressed on the IDTterminal, a variation in the contact resistance is mitigated.

Further, since the wire is not forcibly pushed into the slot of the IDTterminal from its non-normal position, there is no excessive strain onthe inner conductor of the electric wire. Therefore, since excessiveconcentration of stress does not occur in the conductor, it is possibleto prevent degradation of the conductor as well as an increase in thecontact resistance value resulting from contact failure of a part of theconductor.

Further, as a method for connecting a wire applied with an insulation toan IDT connector, the normal position of the wire in relation to the IDTterminal can be ensured by using a method including: a first step ofinserting the wire into a guide hole inside a cover housing andtemporarily locking the wire by a wire normal-position fixing means; asecond step of retaining the wire by a wire holder provided to the coverhousing; and a third step of pressing the wire holder and the coverhousing toward a base housing by applying pressure thereon from theoutside to bring the wire into IDT contact with an IDT terminal, therebybringing a inner conductor of the wire and the IDT terminal intoconduction with each other.

Further, by tapering the forward end portion of the wire insertion holeand then inserting the wire applied with the insulation into the wireinsertion hole thus having a tapered bore, since a repulsion forcegenerated upon abutment against the above-mentioned tapered boreincreases as the wire applied with the insulation is inserted deeperinto the wire insertion hole, temporary locking of the wire can beeffected using the repulsion force.

It is desirable that, when being mounted on the cover housing, theabove-mentioned wire holder is capable of being displaced to a positionwhere it does not interfere with the wire when inserting the electricwire into the guide hole of the cover housing. With such an arrangement,the wire does not abut against the wire-retaining portion so that thewire-retaining portion does not drop off by being pressed on by the wirebefore the wire connection. Moreover, since the advance movement of thewire is not obstructed, it is possible to smoothly insert the wire intothe wire insertion hole and maintain the wire in its normal positionwith respect to the connection direction thereof.

The above-mentioned wire-retaining portion may be guided by adisplacement guiding portion so as to be displaced in a paralleldirection.

It is also possible to provide a plurality of the IDT terminals in thebase housing, with adjacent IDT terminals being staggered relative toeach other in a zigzag pattern with respect to the wire connectiondirection. Such an arrangement prevents the IDT terminals from cominginto contact with each other even if the width of each IDT terminalitself is set to a sufficiently large value from the viewpoint ofmechanical strength, thereby achieving narrower pitches for theconnector.

It is also possible to provide a protective guide plate for protecting awire in a location where the electric wire-retaining portion that hasbeen descended crosses the above-mentioned guide hole and to guide theelectric wire with the protective guide plate during the insertion ofthe wires.

These and other objects, features and advantages of the presentinvention will be clearly understood through a consideration of thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of this detailed description, the reference will befrequently made to the attached drawings in which:

FIG. 1 is a perspective view showing a state immediately before an IDTconnector according to a first embodiment of the present invention isfitted with a receptacle connector, with a cover housing thereof nothaving been incorporated into a base housing;

FIG. 2 is a perspective view of the connectors of FIG. 1 as seen fromthe rear;

FIG. 3 is a perspective view showing a state in which the IDT connectorof FIG. 1 is fitted with the receptacle connector, with the coverhousing thereof having been incorporated into the base housing;

FIG. 4 is a perspective view showing a state immediately beforedismounting the receptacle connector from that shown in FIG. 3;

FIG. 5 is a perspective view showing a state in which the receptacleconnector has been removed from the state shown in FIG. 4;

FIG. 6 is a top plan view of the connector of FIG. 1 in a state beforethe cover housing thereof is incorporated into the base housing;

FIG. 7 is a side view of the connector of FIG. 6 taken along thedirection of arrow VII of FIG. 6;

FIG. 8 is a front elevational view as seen from the direction of arrowVIII of FIG. 7;

FIG. 9 is a rear elevational view as seen from the direction of arrow IXof FIG. 7;

FIG. 10 is a sectional view taken along the line X—X of FIG. 6;

FIG. 11 is a side view showing a state in which the cover housing of theIDT connector according to the first embodiment of the present inventionis incorporated into the base housing;

FIG. 12 is a view as seen from the direction of arrow XII of FIG. 11;

FIG. 13 is a view as seen from the direction of arrow XIII of FIG. 11;

FIG. 14 is a sectional view showing a state in which, from the stateshown in FIG. 10, the cover housing is incorporated into the basehousing;

FIG. 15 is a sectional view taken along line XV—XV of FIG. 3;

FIG. 16 is a sectional view showing a state in which, from the stateshown in FIG. 15, the cover housing is incorporated into the basehousing.

FIG. 17 is a plan view of the cover housing in which a wire holder isindicated by an imaginary line;

FIG. 18 is a sectional view taken along the line XVIII—XVIII of FIG. 17,in which the wire holder is indicated by a solid line;

FIG. 19 is a view as seen from the direction of arrow XIX of FIG. 17, inwhich the wire holder is indicated by a solid line;

FIG. 20 is a view showing a state in which the connector according tothe present invention is pinched by a tool such as pliers or a jig;

FIG. 21 is a plan view of a cover housing according to a secondembodiment of the present invention, which is a view corresponding toFIG. 17;

FIG. 22 is a view as seen from the direction of arrow IIXII in FIG. 21,which is a view corresponding to FIG. 19;

FIG. 23 is a sectional view taken along the line IIXIII—IIXIII of FIG.21, which is a view corresponding to FIG. 18; and

FIG. 24 is a sectional view taken along the line IIXIV—IIXIV of FIG. 21,which is a view showing a state in which the wire holder is added.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will be given of an IDT connector 1 according to a firstembodiment of the invention with reference to FIGS. 1–20. The IDTconnector 1 is a so-called plug connector, which is composed of a basehousing 3 and a cover housing 5 to be overlaid on the base housing 3.

The base housing 3 includes: a terminal chamber 7 surrounded by thecover housing 5 and in which a plurality of terminals 13 are fixed; amating section 9 which is inserted into a receptacle connector 25serving as a mating connector of the IDT connector 1; and a partitionwall 11 located between the terminal chamber 7 and the mating section 9(see FIG. 10).

The terminal chamber 7 defines a bed in which plural (four in thisembodiment) terminals 13 serving as IDT terminals are fixed onto abottom surface 15 thereof (see FIGS. 10, 14 etc.).

Each terminal 13 is stamped and formed from sheet metal of phosphorusbronze. As can be seen in FIG. 10, in its side view, the terminal 13 hasa shape such as obtained by horizontally orienting the question mark“?”. Nickel plating is performed on the base material of the terminal13. Further, in an IDT contact portion 17 that is cut through the outerinsulation and electrically contact with a inner conductor 21 a of anelectric wire 21 (FIGS. 15 & 16) and a contact portion 19 (see FIG. 14)that is mated with the receptacle connector 25 shaped like a hollow box,the portions 17 and 19 each forming a part of the terminal 13, solder,such as tin-lead solder plating and gold plating are performed,respectively, on the nickel-plating layer. A top surface 25 a of thereceptacle connector 25 has a notch portion 25 a 1. The provision of thenotch portion 25 a 1 prevents the receptacle connector 25 from abuttingagainst a main body 5 a of the cover housing 5 when it is mated with theIDT connector 1.

Note that a locking hole 25 b is formed in a side surface of thereceptacle connector 25. Further, the receptacle connector 25 hasterminals 25 c in an inner portion thereof, the terminals 25 c eachbeing in electrical contact with the contact portion 19 of each terminal13. By soldering the terminals 25 c onto a printed circuit printedcircuit board 28, the receptacle connector 25 is fixed onto the printedcircuit board 28.

As can be seen from FIGS. 15 & 16, the IDT contact portion 17 with anIDT contact edge 17 a has a U-shaped configuration. The wire 21 ispress-fitted into a slot 20 of the IDT contact portion 17, which isformed due to the U-shaped configuration. The above-mentioned IDTcontact edge 17 a is formed in the slot 20. The terminal 13 has a baseportion 23 which is a portion extending in the longitudinal direction ofthe terminal 13 from a proximal end portion of the IDT contact portion17. The base portion 23 of the terminal 13 is placed on the base housing3. Extending in an area further ahead of the base portion 23 via anupwardly offset part 18 is the contact portion 19.

By forming the above-mentioned offset part 18 in the terminal 13, thecontact portion 19 is located substantially at the center of the matingsection 19 with respect to the vertical direction (the verticaldirection in FIGS. 10 & 14). This ensures degree of freedom in thedesigning of the recaptacle connector 25 serving as the mating connectorof the IDT connector 1, which ultimately contributes to heightreductions of the both connectors.

The mating section 9 serves as a fitting portion in which the receptacleconnector 25 is fitted from the outside. A passage hole 27 for retainingthe terminal 13 is formed in the partition wall 11 (FIG. 10). Thepassage hole 27 is formed to be somewhat smaller in width than theterminal 13 to allow the terminal 13 to be brought into a close fittherewith. Barb portions may be provided on sides of the terminal 13.

As seen in FIGS. 1–3, a cantilever-like holding arm portion 26 isprovided. The holding arm 26 is fixed at one end near the mating face 9and free at the other end. Formed in the center of the holding arm 26 isa locking claw 26 a which serves to maintain a fitting engagementbetween the receptacle connector 25 and the IDT connector 1 when noexternal force is being applied to the holding arm 26.

When the operator presses the holding arm 26 inwardly (as indicated bythe while arrow of FIG. 3), the locking claw 26 a moves inwardly, sincethe holding arm has elasticity. And the locking claw is released fromthe locking hole 25 b of the receptacle connector 25 (see the change inthe state of the holding arm 26 from that indicated by imaginary linesin FIG. 4 to that indicated by solid lines in the same figure). Unlessthe holding arm 26 is pressed as described above, the state of lockingengagement is maintained (see FIG. 3).

As can be seen from FIGS. 2, 9, 10, etc., the cover housing 5 has in themain body portion 5 a thereof a plurality (four illustrated) of wireinsertion or guide holes 29 into which the electric wires 21 of theabove-mentioned external circuit are inserted. The wire insertion hole29 penetrates longitudinally through the cover housing 5. Further, thefour wire insertion holes 29 are arranged in parallel in the widthwisedirection (the direction orthogonal to the longitudinal direction of thecover housing 5) at equal intervals. In each wire insertion hole 29, theforward end portion thereof as seen in the insertion direction of thewire 21 is tapered to form a tapered bore 30. In the inner surface ofthe guide hole 29, the portion of the tapered surface is graduallyreduced in diameter relative to the diameter of the wire 21 applied withan insulation 21 b.

Further, the cover housing 5 includes: IDT contact slits 33 each forpress-fitting the wire 21 to each IDT contact portion 17 and maintainingthe electrical connection state between the both; and an electric wireholder 31 for maintaining a normal state of the wire 21 during thepress-fitting, which also functions as a strain relief after theelectric connection is established, that is, as a part for protecting alocation where mechanical strength is insufficient beause the insulation21 b is torn off by the IDT contact edge 17 a in establishing the IDTcontact connection, so that an external force such as a tensile force isnot exerted thereon through the wire 21.

The wire holder 31 extends orthogonal to the longitudinal direction ofeach wire insertion hole 29 formed in the main body 5 a. Thus, the coverhousing 5 is provided with an opening 35 for allowing the wire holder 31to be slid in the longitudinal direction of the wire insertion hole 29while being oriented orthogonal thereto (FIGS. 1–7, 10 & 14). Theopening 35 is a through hole penetrating from a top surface 36 of thecover housing 5 to each wire insertion hole 29. The wire holder 31 isguided along the opening 35. Then, by pressing the top of the wireholder 31 in the state where the wire is being inserted into the wireinsertion hole 29, the wire holder 31 moves to a location where it is inclose contact with the top surface of the insulation of the wire 21 andretains the wire 21. In this state, the top surface of the wire holder31 is substantially coplanar with the top surface 36.

The wire holder 31 has on the underside a guide projection 32 forvertically guiding the same (FIGS. 10, 18 & 19). The guide projection 32is a rectangular plate portion extended vertically toward the basehousing 3 from the center of a lower surface 37 of the wire holder 31(FIGS. 18, 19), which opposes the wires 21.

The guide projection 32 extends in the axial direction of the wireinsertion hole 29. Further, the above-mentioned cover housing 5 has aguide slit (guide hole) 38 into which the guide projection 32 isinserted (FIGS. 17, 19). When the guide projection 32 is inserted intothe guide slit 38 to move within the guide slit 38, the holder 31 can bedisplaced between its upper-ready position (shown in FIG. 10 in whichthe holder 31 protrudes from the cover housing 5) and its lower-fixedposition (shown in FIG. 14 in which the holder 31 is received within thehousing 5) in parallel, that is, while maintaining the same orientation.

It should be noted that in the upper-ready position, the wire holder 31does not interfere with the electric wire 21, so that this position canbe referred to as an electric wire non-fixing location. Also, in thelower-fixed position, the holder 31 interferes with the electric wire21, so that this position can be referred to as an electric wire fixinglocation. Because the wire holder 31 is thus displaced in parallelbetween the upper-ready position and the lower-fixed position byinserting the guide projection 32 into the guide slit 38, the guideprojection 32 and the guide slit 38 are referred to as the “displacementguiding portions” in this description. Further, for the purpose ofmaintaining the completely descended state of the holder 31, a lockingclaw 31 a ₁ and a locking claw 5 a ₁, are formed on a side portion ofthe holder 31 and on the main body 5 a of the cover housing 5,respectively. (FIG. 19.)

Further, on the lower surface 37 mentioned above (FIGS. 18, 19), plural(four in this embodiment) recess slots 39 of a minor arc cross-sectionalshape are formed, each in association with the cylindrical surface ofthe insulation 21 a of each wire 21.

The IDT contact slot 33 (FIGS. 1–6, 10 and 14–17) is formed so as toextend orthogonal to the wire insertion hole 29 and be shifted inposition relative to the wire holder 31 with respect to the longitudinaldirection of the wire insertion hole 29. This arrangement is effectivein securing a sufficient sectional area for the IDT contact portion 17that serves as the IDT contact edge, without enlarging the pitch betweeneach electric wire. In other words, this arrangement serves to prevent asituation where the IDT contact portion 17 is excessively deformed andbroken due to a surface tension exerted when the electric wire 21applied with the insulation 21 b is pressed onto the IDT contact edge.

Upon mounting the cover housing 5 to the base housing 3, the IDT contactportion 17 which is attached to the base housing 3 is partially insertedinto the cover housing 5 to reach the wire insertion hole 29 and, at thesame time, it cuts through the outer insulation 21 b of the electricwire 21, whereby the inner conductor 21 a and the terminal 13 arebrought into direct contact with each other.

Mounting of the IDT connector 1 constructed as described above iseffected with the cover housing 5 being received within the base housing3 as shown in FIG. 14, by way of the state shown in FIG. 10 and thestate shown in FIG. 20. As can be seen from FIGS. 15 and 16, pluralengaging protrusions 5 b for maintaining the state in which the coverhousing 5 is received within the base housing 3 are formed on sidesurfaces of the cover housing 5. Further, engaging protrusions 3 b to beengaged with the above-mentioned engaging protrusions 5 b are formed onthe base housing 3.

The engagement between the engaging protrusion 5 b and the engagingprotrusion 3 b prevents the cover housing 5 from becoming dislodged fromthe base housing 3. That is, in the state shown in FIG. 10, the wire 21applied with the insulation 21 b is first inserted into the wireinsertion hole 29 of the cover housing 5. As the wire 21 is pusheddeeper into the wire insertion hole 29, it eventually reaches thetapered bore 30. At that point, since the diameter of the wire 21applied with the insulation 21 b is larger than the diameter of thetapered bore 30, the leading end of the wire 21 is subjected to apressing force, preventing further advance movement thereof. That is, byperforming tapering on the forward end of the wire insertion hole 29,temporary locking of the wire 21 can be effected utilizing the repulsionforce of the wire 21 abutting against the tapered bore 30. At this time,the position in which the wire 21 is temporarily locked and fixed withinthe wire insertion hole 29 is hereafter referred to as a normal positionin the wire connection direction (wire insertion direction).Accordingly, the tapered bore 30 is hereafter referred to as electricwire normal-position fixing means 30. Further, the forward end portionof the IDT contact portion 17 is inserted into the IDT contact slit 33of the cover housing 5.

Next, as shown in FIG. 20, the IDT connector 1 is pinched with a tool 34such as a vice or pliers. At first, an external force F is applied ontothe top surface of the wire holder 31, so that the holder 31 then moveswithin the opening 35 from the electric wire non-fixing location shownin FIG. 10 to a position for pressing on the wire 21.

When the top surface 31 b of the wire holder 31 becomes coplanar withthe top surface 36 of the cover housing 5, the external force F appliedby the tool 34 is exerted on both the wire holder 31 and the top surface36 of the cover housing 5, thus pushing the cover housing 5 toward theterminal chamber 7 of the base housing 3.

As a result, the IDT contact connections to the wires 21 each beingapplied with the outer insulation 21 b are effected at once, so that theinner conductor 21 a (see FIGS. 15 and 16) of each wire 21 comes intodirect contact with the terminal 13.

As has been described above, in the IDT connector 1 according to thisembodiment, the wire 21 applied with the insulation 21 b is insertedinto the wire insertion hole 29 of the cover housing 5, thereby ensuringthe normal position of the wire 2 with respect to the connectiondirection thereof relative to the terminal 13 when the cover housing 5is incorporated into the base housing 3. Further, because the wires 21are locked in place by the wire holder 31 those functions as a strainrelief, the normal location of the wires 21 is maintained.

As described above, the wire 21 is press-fit into the slot 20 of theterminal 13 in an extremely accurate and orderly fashion, therebyeliminating a situation where degradation occurs in the conductor 21 aof the wire 20 from excessive strain, the sectional area of theconductor 21 a is reduced, or the contact resistance varies among therespective press-fitting positions.

In other words, as a method for connecting the wire 21 applied with theinsulation 21 b to the IDT connector 1, the wire 21 is fixed in place byusing a method including: a first step of inserting the wire 21 into thewire insertion hole 29 inside the cover housing 5 and temporarilylocking the electric wire by a taper portion 30 which is electric wirenormal-position fixing means; a second step of retaining the wire 21 inthe wire holder 31 provided to the cover housing 5; and a third step ofpressing the holder 31 and the cover housing 5 toward the base housing 3by applying pressure thereon from the outside to bring the wire 21 intoIDT contact with the IDT terminal 13, thereby bringing the conductor 21a of the wire 21 and the IDT terminal 13 into conduction with eachother. Therefore, it is possible to ensure the normal position of thewire 21 in relation to terminal 13.

Next, a description will be given of a second embodiment of the presentinvention using FIGS. 21–24. A connector according to the secondembodiment is different from the connector according to the firstembodiment only with respect to the cover housing. Therefore, adescription will be given of only the cover housing.

The differences of a cover housing 50 according to the second embodimentfrom the cover housing 5 according to the first embodiment arethree-folds: 1) there are provided plural guide projections for guidingthe wire holder and plural guide slits for engagement with the guideprojections; 2) the guide projection itself is imparted with thefunction of the wire holder; and 3) a protective guide plate is providedat the crossing part between the opening and the wire insertion hole,and the guide slit is formed in the protective guide plate. Therefore, adetailed description thereof is omitted by giving the same referencenumerals to the same or similar parts.

In more detail, as can be seen from FIGS. 21 & 22, at the crossing partbetween the opening 5 where the holder 31 is disposed and the wireinsertion hole 29 is covered with a protective guide plate 62 so as toprotect the wire 21. Thus, the protective guide plate 62 may also bereferred to as a cover portion for the wire 21. In the protective guideplate 62, plural (four in this embodiment) guide slits 58 each having adiamond shape obtained by tapering both ends of an elongate rectangleare formed in the protective guide plate 62.

As illustrated in cross section in FIGS. 22 & 23, the protective guideplate 62 is shaped as a series of continuous arches. The guide slits 58are individually formed with setting the respective apexes of those archportions as centers. On the other hand, as can be seen in FIG. 23, theguide projection 52 is formed as a rectangle in cross section which issomewhat thinner than the guide slit 58.

This arrangement is to prevent the guide projection 52 from interferingwith the guide slit 58. Further, plural protrusions 56 (FIG. 24) areformed on the leading end surface of the guide projection 52, in orderto provide stability by those protrusions 56 when the electric wire 21is pressed and to enable electric wire retention capable of withstandingthe tensile force of the wire 21 (that is, the function as a strainrelief).

With the above-constructed connector according to the second embodimentof the present invention as well, there can be attained basically thesame effects as those of the connector according to the firstembodiment. Concerning an operational effect unique to the presentembodiment, the protective guide plate 62 is provided at the crossingpart between the opening 55 and the wire insertion hole 29, and theguide slit 58 is formed in the protective guide plate 62. Thus, when theguide projection 52 is inserted into the guide slit 58 formed in theprotective guide plate 62 so that the wire 21 is pressed on by the guideprojection 52 and the guide projection 52 thus functions as the wireholder, since the guide slit 58 is closed by the guide projection 52,the insulation material of the wire 21 is not easily pushed outward offthe wire insertion hole 29, which is a feature advantageous inmaintaining the normal position of the wire 21.

As has been described above, according to the present invention, thewire is inserted into the wire insertion hole of the cover housing,thereby ensuring that the wire assumes a normal position in relation tothe IDT terminal when the cover housing is incorporated into the basehousing. Further, since the wire is supported firmly by the wire holder,the normal position of the wire is maintained as it is, making itpossible to bring the wire into IDT contact with the IDT contact edge.Therefore, since the wire is not forcibly pushed into the slot of theIDT terminal from its non-normal position, abnormal deformation or thelike does not occur with respect to the inner conductor of the wire. Asa result, excessive concentration of stress does not take place in theconductor, thereby making it possible to suppress a degradation of theconductor or a variation in the resistance value and also prevent anincrease in the resistance value due to a decrease in the sectional arearesulting from excessive pressing.

1. An IDT connector, comprising: a base housing having a plural ofconductive insulation displacement terminals to which a plurality ofwires applied with outer insulation are press-fitted; a cover housingengageable with the base housing, the cover housing having a pluralityof guide holes which the wires therein; a wire holder for holding saidwires for insertion into the guide holes, wherein said cover housing haswire normal-position fixing means for fixing said wires in a normalposition within said guide holes with respect to a connection directionof said wires, the wire normal-position fixing means including taperedbores that form inner surfaces of said guide holes, diameters of saidtapered bores gradually decreasing relative to diameters of said wiresand, wherein said wires are fixed a normal position in said coverhousing by said tapered bores and are brought into contact with saidinsulation displacement terminals when said cover housing is engagedwith said base housing.
 2. An IDT connector according to claim 1,further including a protective guide plate for protecting said wires,the protective guide plate being disposed is provided in an area of saidcover housing, where the wire holder that is descended crosses saidguide holes, and said protective guide plate covering said wires.
 3. AnIDT connector according to claim 1, wherein a plurality of saidinsulation displacement terminals are provided in said base housing suchthat adjacent terminals are staggered relative to each other in a zigzagpattern with respect to a connection direction of said wires.
 4. An IDTconnector according to claim 1, wherein said wire holder is attached tosaid cover housing, in a manner such that said wire holder is capable ofbeing displaced to a position where said wire holder does not interferewith said wires to be inserted in said guide holes.
 5. An IDT connectoraccording to claim 4, further including displacement guiding portionsthat guide said wire holder during engagement of said cover housing withsaid base housing so that said wires held thereby are displaced in aparallel fashion.